Research On Train To Train Direct Communication Based On Ultra-short Wave

Based on the need of emergency and redundant communication, train to train directcommunication system arises, which can realize the exchange of real-time information such asthe speed, location between tracing trains in the same line only through vehicular communicationequipments, therefore, not only can it be the standby system or emergency communicationsystem to improve the safety of train operation, but also it provides guarantees for trainformation and intelligent transportation.In the thesis, the train-to-train direct communication system is designed, also thecommunication band, communication distance between tracing trains and the structure of theon board transceiver are selected for railway application requirements. Considering thefeatures of the train-to-train direct communication in different application and using theclassic model of radio waves propagation loss, the models of radio waves propagation loss,which are suitable for station, marshalling yards and section respectively, are selected. Thenthe calculated results under different conditions of the receiver power also with simulation areillustrated, which analysis result shows that the train-to-train direct communicationtechnology can be realized. At the same time, the multipath propagation and Doppler effect inradio propagation are discussed and simulated, which results show that the multipathpropagation and Doppler effect lead to serious signal fading.Between mobile terminals, the direct communication channel of train to train is the Ricechannel, which has the line-of-sight component. Then the Doppler shift and Doppler Powerspectrum are analyzed, which results show the pure frequency shift without apparent Dopplerspread in the channel. By Matlab simulation, using the channel model, the first and secondorder statistical properties are discussed, mainly, how the parameters, especially Rice factorand train speed, affect channel fading properties is analyzed that result shows the highfrequency fading in the train to train direct communication channel, so the anti-fadingtechniques is in great need to reduce the signal fading.Because communication nodes are keeping moving, its network is similar to vehiclead-hoc network in the field of the road, but easier than it. This thesis has touched on trainvehicle ad-hoc network, determining the third layer protocol stack model, explaining how thedata to transfer and how the function of the layers to accomplish through the instance, andprobably determining operation mode of the access to control layer and methods to thecompetition of channel.